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Soy Myths

Fact or fiction?

There’s no denying that soy is quite the wonder-bean. It’s a source of complete protein and has a host of other healthful properties. But with so much information available about soy, it’s not always easy to be sure what’s accurate. So we’ve done our research to help you distinguish the truth from the tall tales.

There’s no denying that soy is quite the wonder-bean. It’s a source of complete protein and has a host of other healthful properties. But with so much information available about soy, it’s not always easy to be sure what’s accurate. So we’ve done our research to help you distinguish the truth from the tall tales.

Reality: Soymilk such as Silk® delivers many of the same important nutrients as cow's milk, including calcium, vitamin D and protein. In addition, unlike many types of cow's milk, soymilk is very low in saturated fat and cholesterol-free. Find out more about Silk vs. milk.

Myth: Soy is a major cause of food allergy

Reality: Soy protein is one of the eight most common food allergens; a list that also includes proteins in milk, eggs, peanuts, tree nuts, fish, shellfish and wheat. However, these foods are not equally allergenic. In fact, soy allergy is relatively rare and much less common than milk and peanut allergies.1,2 If you know or suspect you are allergic to soy, consult your doctor for dietary guidelines and always read labels with care.

Myth: Minerals are not absorbed when soy is consumed

Reality: Soybeans—like other legumes and whole grains—contain phytate; a naturally-occurring plant compound that can reduce the absorption of minerals such as calcium and iron. However, research shows that calcium from soymilk is absorbed as well as calcium from cow's milk.3 In addition, new research indicates that in contrast to older thinking, iron absorption from soy is also very good.4

Myth: Soy protein is inferior because it comes from a plant

Reality: Unlike most plant proteins, soy protein is "complete," meaning that it contains all of the essential amino acids—the building blocks of protein—in sufficient quantities to meet the body's requirements.5 The medical and nutrition communities, as well as the FDA, recognize soy protein as equal in quality to animal protein.

Myth: All soy is the same

Reality: Whole soybeans are a nutritious source of protein, fiber, beneficial omega-3 fats and a variety of vitamins and minerals such as folate and potassium. However, not all foods made from the soybean provide all of these beneficial components. Soymilk made from whole soybeans, soynuts, tempeh and edamame are examples of whole soyfoods which better preserve the nutritional attributes of the soybean. Most processed products such as soy supplements and isolated soy protein do not.

Myth: All soymilk is the same

Reality: There are two types of soymilk commonly found on the market: those made from whole soybeans and those made from isolated soy protein. Whole bean soymilk, such as Silk, is made by crushing the bean and removing the indigestible fibrous portions, then blending the resulting "base" with water, flavoring and nutritious fortifications such as calcium. This whole bean process preserves not only the protein but also other important components of the original soybean including isoflavones, essential fatty acids including an omega-3 fat and some fiber. Soymilk made from isolated soy protein is highly processed, made by chemically extracting the protein from the bean, then reconstituting the isolated protein with water and other additives.

Myth: Soy flour and soy protein powder are the same thing

Reality: Soy flour (used in some Silk Light products) is a minimally processed ingredient made by mechanically grinding soybeans. Soy protein powder (isolated soy protein) is a highly processed substance, made by chemically extracting and isolating the protein from the bean.

Myth: Soy upsets your stomach

Reality: While any food can cause sensitivity in some people, clinical studies don't show soy causes more gastrointestinal disturbances than other commonly consumed foods. Furthermore, soymilk is a wholesome and delicious milk alternative for those who can't drink milk due to lactose intolerance. If you know or suspect you are allergic to soy, consult your doctor for dietary guidelines and always read labels with care. Find out more about Silk vs. milk.

Reality: For centuries, Asian women have consumed soy while pregnant. Many human studies have also confirmed that soy is safe for pregnant women. In fact, fortified soymilk like Silk is a delicious and convenient source of many nutrients that are important in pregnancy, including calcium and high-quality protein. Soymilk is also lactose-free, which may be helpful to some pregnant women with lactose sensitivity. If you are pregnant, ask your doctor for advice about a healthy diet. Find out more about Silk vs. milk.

Reality: Soymilk like Silk and other soyfoods can be a nutritious addition to a child's diet. For most children, soymilk can be introduced around the same time dairy milk is typically introduced (usually around age one). Since all children are different, Silk recommends consulting your doctor before changing your child's diet. Silk soymilk is a good source of high-quality protein and provides many of the same nutrients found in milk including calcium, vitamin D, potassium, riboflavin and vitamin B12. Soymilk and other milk alternatives should not be used as infant formula. Find out more about Silk vs. milk.

Myth: Soy doesn't support growth and development in children

Reality: The medical and nutrition communities, as well as government agencies, agree that soy can play a valuable role in a healthy balanced diet for men, women and children alike. Soy is a complete plant protein, meaning that it contains all of the amino acids necessary for optimal human health. Soymilk such as Silk is also an excellent source of calcium and vitamin D: two nutrients especially important for growing kids. Find out more about Silk vs. milk.

Myth: Consuming soy affects sexual development

Reality: There is no human evidence showing that soy affects sexual development. Soy does not affect hormone levels nor does soy contain the hormone estrogen.9,10

Reality: There is no human clinical evidence showing that soy affects sexual development. Soy contains isoflavones, also known as phytoestrogens or "plant estrogens." However, isoflavones are different from the hormone estrogen.

Myth: Soy contains estrogen

Reality: Soy does not contain the hormone estrogen. It does contain isoflavones, which are naturally occurring plant compounds. Isoflavones are classified as plant estrogens but isoflavones are very different from the hormone estrogen.

Myth: Consuming soy affects sexual orientation

Reality: There is no human evidence that soy consumption affects sexual orientation.

Myth: Soy causes or worsens thyroid problems

Reality: The overwhelming amount of clinical research shows that soyfoods do not adversely affect thyroid function in people with normal-functioning thyroids.11 Soy protein may inhibit the absorption of thyroid medication taken by hypothyroid patients, but soyfoods are not contraindicated for individuals who are hypothyroid.12 Patients using thyroid medication should work closely with a doctor to ensure consistent and effective dosing.

Reality: In fact, studies show that among those who consume higher amounts of soy, such as Asian populations, cancer is less likely than in those who consume relatively little soy.13,14 Intriguing evidence in particular suggests that soy reduces risk of breast and prostate cancer. Find out more about the health benefits of soy.

Myth: Soy is not safe for breast cancer patients and survivors

Reality: According to the American Cancer Society, breast cancer patients can consume soyfoods like soymilk, tofu and edamame.15 In fact, a recently published study involving nearly 10,000 breast cancer patients found that higher soy consumption was associated with a 25% reduction in cancer recurrence.16 Find out more about the health benefits of soy.

Myth: Soy increases the risk of heart disease

Reality: In fact, according to the FDA, consuming 25 grams of soy protein per day, as part of a healthy diet low in saturated fat and cholesterol, may help reduce the risk of heart disease.17 Clinical research shows that soy protein directly lowers LDL ("bad") cholesterol.18 Soy also contains omega-3 fatty acids, which have been studied for their role in heart health. Furthermore, plant-based foods like soymilk are often lower in saturated fat and cholesterol than their animal-based counterparts, making them an especially smart choice for a heart-healthy lifestyle. It is clear that soyfoods work through many ways to promote heart health. Find out more about the health benefits of soy.

Myth: Soy damages the immune system

Reality: Clinical evidence shows that soyfoods do not adversely impact the immune system.19